mtd: mtd_oobtest: add bitflip_limit parameter
It is common for NAND devices to have bitflip errors.
Add a bitflip_limit parameter to specify how many bitflips per
page we can tolerate without flagging an error.
By default zero bitflips are tolerated.
Signed-off-by: Roger Quadros <rogerq@ti.com>
Signed-off-by: Sekhar Nori <nsekhar@ti.com>
Signed-off-by: Brian Norris <computersforpeace@gmail.com>
diff --git a/drivers/mtd/tests/oobtest.c b/drivers/mtd/tests/oobtest.c
index edd859d..1fd2cda 100644
--- a/drivers/mtd/tests/oobtest.c
+++ b/drivers/mtd/tests/oobtest.c
@@ -34,8 +34,11 @@
#include "mtd_test.h"
static int dev = -EINVAL;
+static int bitflip_limit;
module_param(dev, int, S_IRUGO);
MODULE_PARM_DESC(dev, "MTD device number to use");
+module_param(bitflip_limit, int, S_IRUGO);
+MODULE_PARM_DESC(bitflip_limit, "Max. allowed bitflips per page");
static struct mtd_info *mtd;
static unsigned char *readbuf;
@@ -115,24 +118,27 @@
return 0;
}
-/* Display the address, offset and data bytes at comparison failure */
-static int memcmpshow(loff_t addr, const void *cs, const void *ct, size_t count)
+/*
+ * Display the address, offset and data bytes at comparison failure.
+ * Return number of bitflips encountered.
+ */
+static size_t memcmpshow(loff_t addr, const void *cs, const void *ct, size_t count)
{
const unsigned char *su1, *su2;
int res;
- int ret = 0;
size_t i = 0;
+ size_t bitflips = 0;
for (su1 = cs, su2 = ct; 0 < count; ++su1, ++su2, count--, i++) {
res = *su1 ^ *su2;
if (res) {
pr_info("error @addr[0x%lx:0x%x] 0x%x -> 0x%x diff 0x%x\n",
(unsigned long)addr, i, *su1, *su2, res);
- ret = 1;
+ bitflips += hweight8(res);
}
}
- return ret;
+ return bitflips;
}
static int verify_eraseblock(int ebnum)
@@ -141,6 +147,7 @@
struct mtd_oob_ops ops;
int err = 0;
loff_t addr = (loff_t)ebnum * mtd->erasesize;
+ size_t bitflips;
prandom_bytes_state(&rnd_state, writebuf, use_len_max * pgcnt);
for (i = 0; i < pgcnt; ++i, addr += mtd->writesize) {
@@ -159,9 +166,11 @@
errcnt += 1;
return err ? err : -1;
}
- if (memcmpshow(addr, readbuf,
- writebuf + (use_len_max * i) + use_offset,
- use_len)) {
+
+ bitflips = memcmpshow(addr, readbuf,
+ writebuf + (use_len_max * i) + use_offset,
+ use_len);
+ if (bitflips > bitflip_limit) {
pr_err("error: verify failed at %#llx\n",
(long long)addr);
errcnt += 1;
@@ -169,7 +178,10 @@
pr_err("error: too many errors\n");
return -1;
}
+ } else if (bitflips) {
+ pr_info("ignoring error as within bitflip_limit\n");
}
+
if (use_offset != 0 || use_len < mtd->ecclayout->oobavail) {
int k;
@@ -188,9 +200,10 @@
errcnt += 1;
return err ? err : -1;
}
- if (memcmpshow(addr, readbuf + use_offset,
- writebuf + (use_len_max * i) + use_offset,
- use_len)) {
+ bitflips = memcmpshow(addr, readbuf + use_offset,
+ writebuf + (use_len_max * i) + use_offset,
+ use_len);
+ if (bitflips > bitflip_limit) {
pr_err("error: verify failed at %#llx\n",
(long long)addr);
errcnt += 1;
@@ -198,7 +211,10 @@
pr_err("error: too many errors\n");
return -1;
}
+ } else if (bitflips) {
+ pr_info("ignoring error as within bitflip_limit\n");
}
+
for (k = 0; k < use_offset; ++k)
if (readbuf[k] != 0xff) {
pr_err("error: verify 0xff "
@@ -237,6 +253,9 @@
int err = 0;
loff_t addr = (loff_t)ebnum * mtd->erasesize;
size_t len = mtd->ecclayout->oobavail * pgcnt;
+ size_t oobavail = mtd->ecclayout->oobavail;
+ size_t bitflips;
+ int i;
prandom_bytes_state(&rnd_state, writebuf, len);
ops.mode = MTD_OPS_AUTO_OOB;
@@ -247,6 +266,8 @@
ops.ooboffs = 0;
ops.datbuf = NULL;
ops.oobbuf = readbuf;
+
+ /* read entire block's OOB at one go */
err = mtd_read_oob(mtd, addr, &ops);
if (err || ops.oobretlen != len) {
pr_err("error: readoob failed at %#llx\n",
@@ -254,13 +275,21 @@
errcnt += 1;
return err ? err : -1;
}
- if (memcmpshow(addr, readbuf, writebuf, len)) {
- pr_err("error: verify failed at %#llx\n",
- (long long)addr);
- errcnt += 1;
- if (errcnt > 1000) {
- pr_err("error: too many errors\n");
- return -1;
+
+ /* verify one page OOB at a time for bitflip per page limit check */
+ for (i = 0; i < pgcnt; ++i, addr += mtd->writesize) {
+ bitflips = memcmpshow(addr, readbuf + (i * oobavail),
+ writebuf + (i * oobavail), oobavail);
+ if (bitflips > bitflip_limit) {
+ pr_err("error: verify failed at %#llx\n",
+ (long long)addr);
+ errcnt += 1;
+ if (errcnt > 1000) {
+ pr_err("error: too many errors\n");
+ return -1;
+ }
+ } else if (bitflips) {
+ pr_info("ignoring error as within bitflip_limit\n");
}
}
